1. Field of the Invention
The present invention relates to a document editor, more particularly, to an art for controlling the display of details according to a logic structure of a graphic element in a document editor for handling the graphic element having the logic structure.
2. Description of the Related Art
In a document editor which handles characters and drawings alike (and has a printing function), it may sometimes be required to suppress the display of details because, for example, what should be focused on is the layout, and information concerning details is unnecessary. Suppressing the details also allows the overall display time interval to be reduced. This requirement often arises when display in a reduced size causes a quantity of information to be displayed for one screen to increase. On the other hand, information concerning details may be needed for the sake of editing or printing. In this case, details must be displayed.
Drawings handled by a document editor in a CASE tool or the like are graphics having logic structures. The document editor executes editings including "move," "copy," and "delete" operations according to the logic structures. Editors that handle graphics having logic structures are characterized by the fact that their modification of a certain edit element may affect other elements.
Graphics having logic structures are, as shown in FIGS. 1a to 1c, graphics in which a certain graphic element and other graphic element have a relationship of "inclusion," a "side-by-side" relationship, or a relationship of "connection." In an example of an inclusive relationship shown in FIG. 1a, graphic elements A1 and A2 included in a graphic element A have the same life span as the graphic element A including them and move together with the graphic element A. In an example of a side-by-side relationship shown in FIG. 1b, side-by-side elements B1 to B4 get larger or smaller independently. If the number or size of a certain element (for example, B2) is changed, the other elements (B1, B3, and B4) are rearranged. In an example of a connective relationship shown in FIG. 1c, if one of connected graphic elements C1 and C2 is moved, a connection line C.sub.12 linking both the elements follows the movement. If one of the connected elements C1 and C2 is deleted, the connection line C.sub.12 is also deleted.
A document editor for handling graphics having the above logic structures must meet the requirements that it can control stages, in which details are displayed, according to logic structures while editing and displaying a document containing characters and drawings, and that it can execute edit irrelevant of the display stages.
Conventionally, a CAD system is a well-known example of an editor enabling stepwise display. The CAD system lies in a concept of "layers." The CAD system can edit drawings or characters for each layer and designate display or non-display for each layer. All drawings or characters in a layer for which display is designated can be displayed superposed on each other in a display screen. FIG. 2 shows an example.
In the CAD system, information residing in all layers is displayed on a display screen. For editing, a layer in which an element to be edited resides must be designated independently. In the example of FIG. 2, for editing a circle, layer 1 must be designated. For editing a dimension, layer 2 must be designated. For editing a note, layer 3 must be designated.
Another known example of an editor enabling display with units of stages can reduce a graphic or character in size arbitrarily during edit and display. A character at a certain reduced size is, however, displayed in the form of a drawing, for example, .quadrature. or .box-solid.. Another known example is a so-called "idea processor," which can display a heading, paragraph, text, and others, with units of stages according to the logic structure of a document.
A system based on a CAD system enabling display with units of stages has a disadvantage that a graphic having a logic structure cannot be handled. In this system, editing is executed in a closed state within each layer. The influence of a result of editing a certain layer cannot be reflected on other layers in a display screen. When it becomes necessary to reflect a result of editing a layer on other different layers, designation of a layer must be changed frequently. This poses a problem that editing and display by an editor cannot be accomplished quickly or efficiently.
Another editors enabling stepwise display have a problem that a graphic having a logic structure cannot be handled. Thus, these editors share the same problems with the CAD system.